1. Field of the Invention
The present invention relates to a process and apparatus for use in cleaning a braebender-type mixing apparatus having two at least partially circular screw cavities.
2. Description of the Prior Art
In the development of polymer containing compositions, it is desirable to produce experimental compositions utilizing conventional processing equipment. The use of conventional processing equipment in the evaluative stage of development of polymer containing compositions is to be preferred as the processing equipment provide the environment in which a composition, if ultimately successful, would be produced on a larger, commercial scale. A screw type extruder having a single, or in the alternative, plural screws, is commonly used in commercial production of a polymeric compositions such as an extruder provides effective heating and mixing of the initial constituents. While such a screw type extruder would be most desirable for use in the development of a polymer containing composition, such extruders typically require sufficient initial constituents on the order of tens of pounds for the production of any meaningful quantity of product sample.
In order to overcome this and other limitations attendant upon the use of screw type extruders, a braebender-type mixer, also known to the art as a bowl mixer or a bowl mixing apparatus, is frequently used to produce small quantities of a polymer containing composition, especially during the development of novel compositions. As is well known to the art, braebender-type mixing apparatus may be advantageously used in the stead of screw type extruders as such braebender-type mixing apparatus typically include two co-rotating or counter-rotating screws wherein each of the screws is housed in an annulus which is nearly circular, or arcuate in configuration and where the screws further have designs of flights which when operating, cooperatively function to assure thorough mixing of the constituents by simulating the shear forces and other mixing effects which would be imparted on the composition in an extruder.
While providing the benefits of approximate of extruder conditions, braebender-type mixing apparatus are nonetheless not without shortcomings. One such deficiency is apparent upon cleaning; the braebender-type mixing apparatus is disassembled and any residue from a composition need be removed. Typically the screws may be removed and the residue thereon removed by applying sufficient heat to burn off any residue, but, in the case of the body and housing which is typically not removable, the use of a wire brush and/or a wire wheel need be used. Such an operation is laborious, and is further complicated by a tendency observed when a wire wheel mounted on a hand holdable electrical drill is used; as the wire wheel spins within one of the two cavities, loosened residue of a polymeric composition is heated by the friction of the brush and shoots to the other cavity where it clings to the inner surface of the other cavity.
What is needed in the art is an improved process and apparatus for use in the cleaning of braebender-type mixing apparatus.